Immune System

Immunology is the study of the body's defense system called the immune system. The system has evolved to prevent harmful organisms from gaining access to the body or to destroy them once they have entered, in order to prevent serious diseases.

The immune system is amazingly complex. It can recognize millions of different enemies, and it can enlist specialized cells and secretions to seek out and destroy each of them. (Substances recognized as foreign that provoke an immune response are called antigens.)

The immune system can be placed into two main categories:

Non-specific Mechanisms such as physical barriers, movement, temperature, chemicals and phagocytic cells and Specific Mechanisms under the control of a group of cells called lymphocytes. These cells and their products are highly specific in that they can recognise foreign cells and mount a response against them. This is referred to as an immune response.

Lymphocytes may be subgrouped into:

T lymphocytes (T cells) that may develop into T helper cells, T killer cells, T memory cells and T suppressor cells. B Lymphocytes (B cells) that may develop into plasma cells and B memory cells. Plasma cells develop from B cells that have become activated following the recognition of a foreign cell or antigen. They produce specific proteins called antibodies or immunoglobulins which recognise and bind to the foreign antigen that had elicited their production.